The present invention relates to folding door apparatus having panels hinged to stack accordionlike above an opening in a building.
Door apparatus having panels hinged along adjacent horizontal edges and arranged to move from a coplanar position in which all panels are vertical, to a stacked position, in which all panels are substantially horizontal, are well known. U.S. Pat. No. 3,618,656 discloses such apparatus suitable for doors having an even number of panels, the upper most in each pair of panels having a pair of first rollers journaled in a pair of brackets on opposite ends thereof. All first rollers ride in a pair of vertical first trackways fixed to the building. In order to support the panels in the stacked position, each of the brackets has a finger-like extension which rotates into position over a respective fixed stud as the respective panel rotates into the horizontal or stacked position. In order to assure that the panels rotate into position in such a manner that the brackets engage only their assigned studs without jamming against any therebelow, the uppermost of each pair of panels also carries a pair of second rollers. Each pair of second rollers rides in its own respective pair of vertical trackways which are specially formed to effect the desired sequence of panel rotation. The panels are raised by a cable attached to the lowermost panel and extending beyond the door panels into an open area.
U.S. Pat. No. 3,757,845, incorporated herein by reference, represents an improvement over the above described patent insofar as the cables extend between the first trackways and the building, and the second rollers ride in a single pair of opposed second trackways. Each second trackway has a vertical portion which parallels the first trackway and an angled portion which diverges rectilinearly therefrom. This simpler construction is made possible in part by brackets wherein the second rollers are spring biased to move substantially parallel to the plane of the respective panel. While solving the problems of the exposed cable and multiple trackways, this apparatus requires very careful field assembly to assure that the finger-like extensions rotate smoothly into position over the studs. Tolerances in the system change with use so that adjustment is eventually required. Further, the finger-like extensions extend into the path of the cable and thus are abraded by the cable during opening and closing of the door.